Follicular lymphoma, although common in adults, is rare in children. Pediatric follicular lymphoma has a more favorable prognosis than adult follicular lymphoma, even though it is often of higher grade. Children with follicular lymphomas are generally at a lower clinical stage, respond well to less aggressive therapy, and have a better survival than adults. Follicular lymphoma must be distinguished from reactive follicular hyperplasia, which it may mimic. Immunohistochemical and molecular markers serve to facilitate this distinction, as well as careful attention to clinical and morphologic details. It is important to recognize pediatric follicular lymphoma as a unique clinicopathologic entity to properly diagnose and manage these patients. It may represent a subset of follicular lymphoma with a particularly good prognosis.
Indeterminate cells are considered by many to be pre-Langerhans cells as they mimic Langerhans cells in certain morphologic and immunophenotypic aspects. Indeterminate cells express CD1a and S-100 but lack Langerin expression (Langerin is used as an immunohistochemical substitute for electron microscopy for the detection of Birbeck granules). Migration of Langerhans cells to the lymph nodes through the dermal lymphatics to present skin antigens to T lymphocytes has been well defined before; however, the migration and the identification of indeterminate cells in lymph node has not been investigated before. In our study, we attempt to investigate the presence of indeterminate cells in normal lymph nodes and in lymph nodes with dermatopathic lymphadenitis and analyze their possible coexistence with Langerhans cells. We examined 9 cases of normal skin, 7 cases of normal lymph nodes (both normal skin and normal lymph nodes are obtained from mastectomy specimens), and 5 cases of reactive lymph nodes with dermatopathic lymphadenitis, for the presence of indeterminate cells. A set panel of immunostains was used that included CD1a, S-100, Langerin, CD3, and CD20. Indeterminate cells were defined as CD1a+, S-100+, and Langerin-, whereas Langerhans cells were defined as CD1a+, S-100+, and Langerin+. Scattered indeterminate cells were identified in most lymph nodes with dermatopathic lymphadenitis, but only in those normal lymph nodes that showed paracortical hyperplasia or expansion, whereas Langerhans cells were identified in both.
The increasing prevalence of infections caused by derepressed AmpC mutants that constitutively produce high levels of the AmpC enzyme is an emerging therapeutic challenge. This study aimed to evaluate the sensitivity and specificity of a novel rapid and practical phenotypic screening method for derepressed AmpC έ-lactamase production. We studied 110 gram-negative bacilli that exhibited a range of resistance mechanisms to β-lactam antibiotics: 98 Enterobacteriaceae, 8 Acinetobacter baumannii complex, and 4 Pseudomonas aeruginosa. Of the bacilli, 61 exhibited wild-type AmpC and 49 were derepressed AmpC producers. Bacterial colonies from blood, chocolate, Mueller-Hinton, and MacConkey agar were tested. By using a sterile wooden stick, the bacterial colonies were touched/pressed onto a BD BBL DrySlide Nitrocefin (Becton Dickinson, Franklin Lakes, NJ) slide 3 times. The stopwatch was started simultaneously with the first addition of the bacteria to the slide. The results were considered positive when the chromogenic indicator turned pink, and the stopwatch was stopped. The testing was performed blindly. The timed touch method with a cutoff of 8 seconds detected 98% of derepressed producers of AmpC; 5 wild-type organisms had a time of 8 seconds or less. Using colonies grown on chocolate agar, the results are as follows: sensitivity, 98%; specificity, 92%; positive predictive value, 91%; negative predictive value, 98%; and accuracy, 95%. Mutation of the AmpD gene can result in hyperproduction of AmpC β-lactamase, resulting in resistance to all cephalosporins except cefepime. Through plasmid transfer, derepressed AmpC genes have been found in many gram-negative bacteria. A method that could predict the presence of derepressed AmpC genes from primary growth days before identification and susceptibility testing could provide valuable clinical guidance. The timed touch method using a BD BBL DrySlide Nitrocefin slide could provide critical information to clinicians at least a day earlier than conventional testing. Category:Medical Microbiology
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